mpeg2enc/putbits.c

   1 /* putbits.c, bit-level output                                              */
   2
   3 /* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */
   4
   5 /*
   6  * Disclaimer of Warranty
   7  *
   8  * These software programs are available to the user without any license fee or
   9  * royalty on an "as is" basis.  The MPEG Software Simulation Group disclaims
  10  * any and all warranties, whether express, implied, or statuary, including any
  11  * implied warranties or merchantability or of fitness for a particular
  12  * purpose.  In no event shall the copyright-holder be liable for any
  13  * incidental, punitive, or consequential damages of any kind whatsoever
  14  * arising from the use of these programs.
  15  *
  16  * This disclaimer of warranty extends to the user of these programs and user's
  17  * customers, employees, agents, transferees, successors, and assigns.
  18  *
  19  * The MPEG Software Simulation Group does not represent or warrant that the
  20  * programs furnished hereunder are free of infringement of any third-party
  21  * patents.
  22  *
  23  * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
  24  * are subject to royalty fees to patent holders.  Many of these patents are
  25  * general enough such that they are unavoidable regardless of implementation
  26  * design.
  27  *
  28  */
  29
  30 #include <stdio.h>
  31 #include "config.h"
  32 #include "global.h"
  33
  34 extern FILE *outfile; /* the only global var we need here */
  35
  36 /* private data */
  37 static unsigned char outbfr;
  38 static int outcnt;
  39 static int bytecnt;
  40
  41 void slice_initbits(slice_engine_t *engine)
  42 {
  43         engine->outcnt = 8;
  44         engine->slice_size = 0;
  45 }
  46
  47 void slice_testbits(slice_engine_t *engine)
  48 {
  49         int i;
  50         printf("slice test size %x outcnt %d outbfr %x\n", engine->slice_size, engine->outcnt, engine->outbfr << engine->outcnt);
  51 /*
  52  *      for(i = 0; i < engine->slice_size; i++)
  53  *              printf("%02x ", engine->slice_buffer[i]);
  54  *      printf("%x\n", engine->outbfr << engine->outcnt);
  55  */
  56 }
  57
  58 void slice_putc(slice_engine_t *engine, unsigned char c)
  59 {
  60         if(engine->slice_size >= engine->slice_allocated)
  61         {
  62                 long new_allocation = (engine->slice_allocated > 0) ? (engine->slice_allocated * 2) : 64;
  63                 unsigned char *new_buffer = calloc(1, new_allocation);
  64                 if(engine->slice_buffer)
  65                 {
  66                         memcpy(new_buffer, engine->slice_buffer, engine->slice_size);
  67                         free(engine->slice_buffer);
  68                 }
  69                 engine->slice_buffer = new_buffer;
  70                 engine->slice_allocated = new_allocation;
  71         }
  72         engine->slice_buffer[engine->slice_size++] = c;
  73 }
  74
  75 void slice_putbits(slice_engine_t *engine, long val, int n)
  76 {
  77         int i;
  78         unsigned int mask;
  79
  80         mask = 1 << (n - 1); /* selects first (leftmost) bit */
  81
  82         for(i = 0; i < n; i++)
  83         {
  84         engine->outbfr <<= 1;
  85
  86         if(val & mask)
  87                 engine->outbfr |= 1;
  88
  89         mask >>= 1; /* select next bit */
  90         engine->outcnt--;
  91
  92         if(engine->outcnt == 0) /* 8 bit buffer full */
  93         {
  94                 slice_putc(engine, engine->outbfr);
  95                 engine->outcnt = 8;
  96                         engine->outbfr = 0;
  97         }
  98         }
  99 }
 100
 101 /* zero bit stuffing to next byte boundary (5.2.3, 6.2.1) */
 102 void slice_alignbits(slice_engine_t *engine)
 103 {
 104     if(engine->outcnt != 8)
 105         slice_putbits(engine, 0, engine->outcnt);
 106 }
 107
 108 void slice_finishslice(slice_engine_t *engine)
 109 {
 110         int i;
 111         slice_alignbits(engine);
 112
 113         if(!fwrite(engine->slice_buffer, 1, engine->slice_size, outfile))
 114         {
 115                 perror("Write error");
 116         }
 117         bytecnt += engine->slice_size;
 118 }
 119
 120
 121
 122 /* initialize buffer, call once before first putbits or alignbits */
 123 void mpeg2_initbits()
 124 {
 125         outcnt = 8;
 126         bytecnt = 0;
 127 }
 128
 129
 130 /* write rightmost n (0<=n<=32) bits of val to outfile */
 131 void mpeg2enc_putbits(val,n)
 132 int val;
 133 int n;
 134 {
 135   int i;
 136   unsigned int mask;
 137
 138   mask = 1 << (n-1); /* selects first (leftmost) bit */
 139
 140   for (i=0; i<n; i++)
 141   {
 142     outbfr <<= 1;
 143
 144     if (val & mask)
 145       outbfr|= 1;
 146
 147     mask >>= 1; /* select next bit */
 148     outcnt--;
 149
 150     if (outcnt==0) /* 8 bit buffer full */
 151     {
 152       putc(outbfr,outfile);
 153       outcnt = 8;
 154       bytecnt++;
 155     }
 156   }
 157 }
 158
 159 /* zero bit stuffing to next byte boundary (5.2.3, 6.2.1) */
 160 void alignbits()
 161 {
 162   if (outcnt!=8)
 163     mpeg2enc_putbits(0,outcnt);
 164 }
 165
 166 /* return total number of generated bits */
 167 double bitcount()
 168 {
 169         return (double)8 * bytecnt + (8 - outcnt);
 170 }